Electro-optical relay



Dec. 22, 11942. H. R. LEVY ELECTRO-OPTICAL RELAY Filed Oct. 25., 1939 2 Shuts-Sheet l INVENTOR. HA/vs RuDoLF LEVY lilw 22, 1942. H. R. LEVY 2,306,272

ELECTRO-OPTICAL RELAY Filed 001;. 25, 1939 2 Sheets-Sheet 2 INVENTOR. hAA/J kunozr lEVY atentc r 22, all

ELECTRU-OPTKC RELAY Hans ltudoli lLevy, Golders Green, London, England Application Uctober 25, 1939, Serial No. 301,309

in Germany September 29, 1938 13 Claims.

The present invention relates to an electrooptical relay, by means of which an image, formed by invisible rays such as infra-red rays, heat rays, ultra-acoustic (supersonic) rays, is transformed into an image formedby visible rays.

It is an object of the invention to improve similar known relays.

It is a further object to provide such a relay for transforming an invisible image formed by infra-red rays of a wave-length greater than 1.4 1, and preferably of a wave-length between 2; to 10,11. Such wave-lengths are particularly adapted to penetrate fog and mist and, thus the relay according to the invention may advantageously be used for signalling through fog and mist for navigatory or aeronautical purposes.

It is a specific object of this invention to provide a relay which enables an invisible image formed by electromagnetic micro-waves, i. e., waves of a greater lengththan infra-red waves and immediately adjacent thereto in the spectrum, to be transformed into a visible image.

A still further object of .the invention is to provide a relay which enables an invisible image formed by mechanical supersonic waves to be transformed into a visible image.

Another object of the invention is to arrange the electro-optical relay in such a manner that the visible image obtained is substantially not blurred by the scanning of the devices sensitive to the invisible rays.

Other objects and advantages of the invention will become apparent lrom the specification as it proceeds in connection with the attached drawing in which:

Fig. 1 illustrates, in section, an embodiment of the invention, and

Fig. 2 shows, on an enlarged scale, a modification of a detail of Fig. 1.

Referring now to Fig. 1, there is provided, in an exhausted container l, a great number of thermo-oouples t, t, t, shown for the sake of clarity). Each thermocouple consists of at least one union of a pair of conductors of dissimilar metal joined together at a small spot, for producing an electromotive force across said spot by the action of heat on said spot. For example each thermocouple may consist, as is known per se, of an iron and a constantan wire which are soldered together at the points 2', t, t. Alternatively, each thermo-couple may consist of a plurality of iron wires such as it, it and'constantan wires (only three of which are.

' ments, the soldering points are arranged as close together as is conveniently possible and substantially in a plane in which the image formed by the invisible rays lies. In the container i, a

window it is provided which is permeable to the invisible rays employed and may, for example consist of rock salt or sylvin in the case of infrared rays being employed. One terminal of each thermo-couple is connected to a common metal plate 5, the other terminals being connected to metal wires 1, 8, 9 (which may consist of nickel or steel) having thickened ends l, 8', 9'. The metal wires are coated with a thin layer of insulating material Iii, ii, i2 and are inserted in holes provided in the plate 5, so that the wires 1, t, 9 are supported by, but insulated; from, the plate 5. Eachwire l, t, 9 constitutes together with the common metal plate 5 a small electric condenser which may accumulate electric charges generated by the respective thermo-couple ii, 3 or d. The metal plate 5 is earthed at t. The thickened ends if, t, 9, are coated with a photo-electric substance for example potassium or caesium, which emits electrons under the influence of light. Adjacent to the ends l, t, t a positively biased grid electrode it is provided. The walls it of the container l are matted or made opaque whereas the part lid is transparent, so that a fluorescent screen it arranged within the container l on that side of the electrode it which is remote from the plate 5 may be observed through the window ll. The container i comprises an extension it closed by a window it, which is permeable to light rays emitted from a discharge device it. The discharge device i5 is fed from a source of voltage A through a resistance it. A condenser it" connects the two electrodes of the discharge device. In known manner the discharge device it is intermittently discharged in quick succession, the period of the discharges being determined by the condenser it" and the resistance It. The light emitted is collected by a lens It. Preferably, the lens it is made of quartz. A violet filter ll is provided which transmits light rays of the short wave range of the spectrum. The working of the device is as follows.

When an infra-red image is formed in the plane of the soldering points 2, 3', t of the thermo-couples t, it, t by'infra-red rays reaching the soldering points through the window it, the thermo couples create electric charges,

which are accumulated in the small condensers nformed by the plate t and the wires 1, t, t. The

charges are accumulated in the small condensers during each time interval between two successive I discharges of the light source Ill. The charge of each condenser corresponds to the intensity of the infra-red image at the spot of each of the soldering points 2', 3', d. When the device It is discharged a light beam impinges, at the same instant on all ends 1', t, 9' of the wires 1, d, 9.

I whereby the photo-electric substance covering image corresponding to the invisible image formed in the plane of the soldering points 2',

3, l. Coils 2| serve in a known manner to focus the electrons on the fluorescent screen.

. The visible, image formed on the screen I l may be observed through the window 40. The matting oi the container I prevents light emitted from the light source It from influencing the screen It directly.

Modifications are possible. For example, in the embodiment of Fig. 1 an electron intensifier (known per se) may be interposed between the electrode It and the screen it.

Again, instead of forming the invisible image by infra-red rays it may be formed by Hertzian waves of a wave length up to .a few'centimeters or by ultra acoustic i. e. mechanical waves,which are able to actuate the thermocouples when impinging on the soldering points 2', 3', L. If used for the detection of supersonic waves, the thermo-couples are preferably surrounded by a material absorbing sound, as is known per se, such as india rubber, fibrous material, pitch. In operation, the supersonic waves are absorbed by the material, thereby creating heat which acts on the sensitive spots 2', 3', t, of the thermo-couples and creates electric charges in the condensers formed by the plate 5 and the wires 1, 8, 9.

The light source It may be replaced by an electron gun provided within the container I or by a source of ions, which explores the ends I. 8', 9' instantaneously but intermittently. It will be appreciated that the light beam, the elec tron beam, or the ion beam, exploring the ends 1', 8', 9', is prevented from reaching the sensitive spots 2', 3', 4', by the plate 5, thus preventing these spots from being affected by the exploring beam, which would cause the visible image to be blurred.

The container I may be kept at a constant low temperature in order to enhance the effect of the invisible rays on the thermo-couples. The thermo-couples may be provided, if desired, outside the container I. One or both of the pair of conductors of each thermo-couple may be coiled in the fashion of a coiled incandescent filament, the other conductor, or a lead to a terminal of the thermo-couple, passing axially through the coil. This embodiment is preferred when the invisible image is formed by electromagnetic micro-waves, in which case the thermo-couple forms a resonator which may be tuned to the micro-waves.

Obviously, the plate 5 may be subdivided for simplifying the mounting of the relay.

aaoaava The devices according to this invention may be operated in connection with amplifiers, voltage generators or the like which are already'provided for example on vehicles, vessels, aircraits for other purposes, such as wireless communication purposes, navigational or aeronautical purposes.

I claim:

1. In an electro-optical relay for transforming a primary image formed by invisible rays into a secondary image formed by visible rays, a plurality of thermo-couples, each consisting of at least one union of a pair of conductors of dissimilar metals joined together at a spot for producing an electromotive force across said spot by the action of heat on said spot, the parts sensitive to the invisible rays of said thermo-couples being arranged in a surface substantially coinciding with the surface of the primary image when formed to create between the terminals oi each thermo-couple an electric charge correspending to the local intensity of the invisible rays acting on each thermo-couple; means for intermittently discharging said thermo-couples; and means for converting the discharges into the secondary image.

2. In an electro-optical relay for transforming a primary image formed by invisible rays into a secondary image formed by visible rays comprising a plurality of thermo-couples, each co'nsisting of at least one union of a pair of conductors of dissimilar metals joined together at a spot for producing an electromotive force across said spot by the action of heat on said spot, the parts sensitive to the invisible rays of said thermocouples being arranged in a surface substantially coinciding with the surface of the primary image when formed to create between the terminals of each thermc-couple an electric charge corresponding to the local intensity of the invisible rays acting on each thermo-couple; a plurality of electric. condensers connected electrically to the terminals of said thermo-couples. one to each, for storing the electric charges; -means for intermittently discharging said condensers; and means for converting the discharges into the secondary image.

3. ,In an electro-optical relay for transformin a primary image formed by invisible rays into a secondary image formed by visible rays comprising. a plurality of thermo-couples each consisting of at least one union of a pair of conduc tors of dissimilar metals joined together at a spot for producing an electromotive force across said spot by the action of heat on said spot, the parts sensitive to theinvisible rays of said ihermo-couples being arranged in a surface substantially coinciding with the surface of the primary image when formed to create between the terminals of each thermo-couple an electric I charge corresponding to the local intensity of the invisible rays acting on each thermo-couple; a plurality of electric condensers connected electrically to the terminals of said thermo-couples. one to each, for storing the electric charges: photo-electric coatings provided on at least parts of those electrodes of said condensers which are, in operation, negatively charged; means for intermittently releasing electrons from said coatings and thereby discharging said condensers: means for accelerating said electrons; and means for converting the discharges into the secondary image.

4. In an electro-optical relay for transforming a primary image formed by invisible rays into a asoaavs rho-couples being arranged in a surfacdisubstantially coinciding with the surface ,of. the

primary image when formed to create between the terminals of each thermo-coupie an electric charge corresponding to the local intensity of the invisible rays acting on each thermo-couple; a plurality of electric condensers connected electrically to the terminals of said thermo-couples,

cally connected to said plate; and a plurality of conducting members inserted in the perforations of said plate but electrically insulated therefrom, said members being electrically connected to the negative terminals of said thermo-couples, one to each, said photo-electric coatings being provided at least on portions of said members.

, 59. An electro-optical relay as defined in claim 5.-'wherein said condensers comprise a perforated electrically conducting plate inside said container, the positive-terminal of each 7 of said thermocouples being electricallyconnected to said plate;

lease electrons therefrom and thereby to discharge said condensers; means for accelerating said electrons; and means for converting the discharges into the secondary image.

5. An electro-optical relay for transforming a primary image formed by invisible rays into a secondary image formed by visible rays comprising an evacuated container; a window permeable to the invisible rays in said container; a plurality of thermo-couples inside said container, each consisting of at least one union of a pair of condoctors of dissimilar metals joined together at a spot for producing an electromotive force across said spot by the action of heat on said spot, the parts sensitive to the invisible rays of said thermo-couples being arranged in a surface substantially coinciding with the surface of the primary image when formed to create between the terminals of each thermo-couple an electric charge corresponding to the local intensity of the invisible rays acting on each thermo-couple; a plurality of electric condensers connected electrically to the terminals of said thermo-couples, one to each, for storing the electric charges; photo-electric coatings provided on at least parts of those electrodes of said condensers which are, in operation, negatively charged, 'said coatings being adapted to emit electrons under the infiuence of light; a window permeable to light in said container; at light source arranged outside said container to illuminate said photo-electric coatings intermittently through said lastmentionecl window to release electrons from said coatings and thereby to discharge said condensers; means for accelerating said electrons; and means for converting the discharges into the secondary image.

t. An electro-optical relay as defined in claim 5, wherein said means for converting the discharges into the secondary image comprise a fluorescent screen arranged in said container so as to be encited by electrons when emitted from said coatings; means being provided for focussing said electrons on said fluorescent screen.

'i. The combination as defined in claim 4, wherein said means for converting the discharges into the secondary image, comprise a fluorescent screen arranged so as to be excited by electrons when emitted from said coatings.

d. The combination as defined in claim 4. wherein said condensers comprise a perforated electrically conducting plate, the positive terminal of each of said thermo-couples being electrianda plurality ofcon'ducting members inserted in the perforations'ofsaid plate but electrically insulated therefrom, said members being electrically connected to the negative terminals of said thermo-couples, one 'to each, said photo-electric coatings being provided at least on portions of said members.

10. As an article of manufacture, an evacuated container, at least in part permeable to invisible rays and at least in part permeable to visible rays. containing a plurality of thermo-couples, each consisting of at least one union of a pair of conductors of dissimilar metals joined together at a spot for producing an electromotive force across said spot by the action of heat on said spot, the parts sensitive to the invisible rays of said thermo-couples being arranged in a surface adj acent the part of said container that is permeable to the invisible rays; a perforated electrically conducting plate connected electrically to one terminal of each of said thermo-couples; a plurality of conducting members inserted in the perforations of said plate but electrically insulated therefrom to constitute, together with said plate, a plurality of condensers for storing electric charges created by said thermo-couples when excited by the invisible rays, said members being electrically connected to the other terminals of said thermocouples, one to each; photo-electric coatings adapted to emit electrons under the influence of light and provided at least on a portion of each of said members: a fluorescent screen; means for accelerating towards said screen electrons when emitted by said photo-electric coatings; said fluorescent screen being arranged adjacent the part of the container which is permeable to visible rays; and leading-in wires for applying biasing voltages to said plate and said electrode.

11. As an article of manufacture, an evacuated container, at least in part permeable to invisible rays and at least in part permeable to visible rays, containing a plurality of thermo couples, each consisting of at least one union of a pair of conductors of dissimilar metals joined together at a spot for producing an electromotive force across said spot by the action of heat on said spot, the parts sensitive to the invisible rays of said thermo-couples being arranged in a surface adjacent the part of said container that is permeable to the invisible rays; a perforated electrically conducting plate connected electrically to one terminal of each of said thermo-couples; a plurality of conducting members inserted in the perforations of said plate but electrically insulated therefrom to constitute, together with said plate, a plurality of condensers for storing electric charges created by said thermo-couples when excited by invisible rays, said members being electrically connected to the other terminals of said thermocouples, one to each, photo-electric coatings adapted to emit electrons under the influence of light and provided at least on a portion of each of said members; and leading-in wires for makinn electric connections with said plate and said electrode from the outside of said container.

12. The combination as defined in claim 4; and comprising a luminous discharge device adapted to be discharged intermittently; and an optical system for collecting light, when emitted by said discharge device, on said coatings. v

13. In an electro-optical relay for transforming a primary image formed by invisible rays into a secondary image formed by visible rays comprising a plurality oi theme-couples, each consisting of at least one union of a pair of conductors of dissimilar metals joined'together at a spot for producing an eiectromotive force across said spot by the action of heat on said spot, the parts sensitive to the invisible rays of said the rmo-couples being arranged in a surface substantially coinciding with the surface oi the primary image when formed to create betweenthe terminals of each aeoaava thermo-couple an electric charge corresponding to the local intensity of the invisible rays acting on each theme-couple; a plurality of electric condensers connected electrically to the terminals of said thermo-couples, one to each, for storing the electric charges; photo-electric coatings provided on at least parts of those electrodes of. said condensers which are, in operation negatively charged, said coatings being arranged outside the surface oi said sensitivejparts; means for intermittently releasing electrons from said coatings and thereby discharging said condensers; screenin; means arranged between the surface of said sensitive parts and said coatings for preventing said releasing means when operating from afiecting said sensitive parts; means for accelerating said electrons; and means for converting the discharges into the secondary image.

HANS RUDOLF LEVY; 

